Recently, an optical information recording and reproducing apparatus is used whereby information can be recorded and reproduced at a high density on an optical recording medium using a light beam from an optical pickup instead of recording and reproducing information using a magnetic head.
A disc-like recording medium (which shall be mentioned as a disc hereinafter) has tracks which are formed concentrically or spirally.
Now, as disclosed, for example, in a Japanese patent application laid open No. 37743/1982, conventionally, in case the number of tracks from the present track to an objective track (or desired track) is several tens of tracks, the optical pickup will access the objective track by a track jump. First of all, the controller will read the address number of the now held track (i.e., present track), will calculate a difference in address number from the address number of the objective track and will designate the value of the difference as a track jump command. When the track jump of the designated number ends, the coincidence of the address number of that track with the address number of the objective track will be confirmed and the access operation (seeking operation) will end.
Now, as shown in FIG. 1, in a spiral disc 1, as the track continues spirally, a different track number (address number) will be alotted in the position where one rotation has been made and the recording region is distinguished.
In a spiral disc, when a predetermined track is to be maintained, a mechanical index, provided in response to a position at which the track number is different, will be detected. The track will be maintained by making a kick back operation 2 of returning the pickup to the previous track position for each rotation as shown in FIG. 1.
However, in a spiral disc, when passing a region of a kick back while a track jump is being carried out, since the track jump is preferred to be made witout making a kick back, the number of tracks to reach the objective track will be different from the first designated number of tracks. For example, in FIG. 1, when seeking tracks Nos. 1 to 4, the number of jump commands will be 3. In such a case, as shown by a reference symbol A, in case a track jump is made outside a region in which a kick back is made, that is, a boundary in which the track number varies, an access to the objective track No. 4 will be able to be made but, as shown by a reference symbol B, if a track jump is made while passing through the region in which the track number varies, the track number will be 5 (rather than track number 4) after the track jump. Therefore, after the track jump ends, when the controller confirms the track address number, it will be different from that of the objective track and therefore a track jump command will have to be issued again to make a track jump. Therefore, there is a defect that a long time can occur until an access to the objective track is made.